NSP offers heterobifunctional Folate PEG NHS products (Folate-PEG-NHS, Folic acid-PEG-NHS) with high quality. Folic acid, or vitamin B9, can selectively bind to folate receptor, while the NHS ester can reactive with amine-containing moieties in alkaline conditions quickly and efficiently. This reaction allows attachment of folic acid ligand to proteins, antibodies, peptides or particle surfaces. The PEG moiety in the heterofunctional PEG derivatives provides water solubility, biocompatibility, and flexibility. Folic acid functionalized substrates have been used for targeted drug delivery, imaging, and bio-assay development.